We make every effort to ensure the data presented here is accurate based on the best available information currently on file with DEC. It is therefore subject to change as new information becomes available. We recommend contacting the assigned project staff prior to making decisions based on this information.

Problems/Comments

During closure by removal of regulated underground storage tanks, diesel range hydrocarbons (DRO) and gasoline hydrocarbons (GRO) were detected in soil samples collected at the water table interface three feet below the ground surface. The highest DRO and GRO concentrations detected in soil were stated as 16,000 mg/kg and 640 mg/kg respectively, however benzene was not detected. The ADEC cannot validate the data; a laboratory report for this data is not available.
The fall 2007 investigation re-assessed residual soil contamination next to the former gasoline UST where a 1998 UST closure assessment found a “hot spot” of elevated DRO. Soil borings HB04 and HB05 were advanced at the same location as the “hot spot” mid-way in the length of the west side of the former gasoline UST and mid-way in the length of the east side of the out-of-service regulated waste oil UST. No soil discoloration or fuel odor was noted in soil cuttings. The benzene result in the HB04 soil sample was slightly above its migration to ground water cleanup level (0.00295 mg/kg) with DRO non-detect. DRO concentration in soil reached 49.2 in HB05 but benzene was not detected. Monitoring well MP1 was installed in HB05 and all analytes in the ground water sample were either below instrument detection or below Table C cleanup levels.

Action Information

Action Date

Action

Description

DEC Staff

4/8/2000

Leaking Underground Storage Tank Cleanup Initiated - Petroleum

4/7/08 Administrative update

Evonne Reese

4/8/2000

Leaking Underground Storage Tank Release Confirmed - Petroleum

LUST Site created in CSP for source area ID 77852 1500 gallon diesel and 500 gallon gasoline USTs removed. DRO detected at 16,000 ppm at one sample location. No soil excavated.

Site tickler update - No action per now based on Carnahan's email this date (saved in Outlook site folder for Sitka Halibut Point Maintenance Station). Check back with DOT early in new fiscal year to see if any of the SE sites are higher on their budget prioritizaton list.

Bill Janes

2/20/2002

350 Determination

Administrative update: a 350 determination has been established for this site.

Kristin Thompson

2/20/2002

Cleanup Level(s) Approved

18 AAC 75.350 determination and 10X Rule on groundwater and soil is agreed upon by the property manager

Regulated underground storage tank soil and ground water assessment for tank closure and development of a conceptual site model was completed at the facility. ADEC reviewed and approved ADOT&PF Airport Maintenance Shop Site Assessment Report Sitka, Alaska by SLR. The Report indicates that target analytes were detected in soil and ground water below applicable Method Two screening levels with the exception of benzene in soil from HB04 at 0.00295mg/L.

Bruce Wanstall

10/21/2008

Conceptual Site Model Submitted

SLR 2007 Report data determined that since ground water at the facility is shallow (4.1 feet below ground surface) and the underground storage tanks are in the zone of ground water influence, a direct release from the existing buried tanks could occur. Even though no contaminant concentrations exceeded cleanup levels, ground water is considered an impacted media with regards to the conceptual site model. Other completed exposure pathways include incidental soil ingestion or dermal contact and indoor or outdoor air. The level of risk is abated by the presence of an asphalt cap across the site.

Bruce Wanstall

2/25/2009

Exposure Tracking Model Ranking

A new updated ranking with ETM has been completed for source area 77852 USTs.

Bruce Wanstall

3/11/2009

Final Cleanup Report Reviewed

The fall 2007 investigation re-assessed residual soil contamination next to the former gasoline UST where a 1998 UST closure assessment found a “hot spot” of elevated DRO. Soil borings HB04 and HB05 were advanced at the same location as the “hot spot” mid-way in the length of the west side of the former gasoline UST and mid-way in the length of the east side of the out-of-service regulated waste oil UST. No soil discoloration or fuel odor was noted in soil cuttings. The benzene result in the HB04 soil sample was slightly above its migration to ground water cleanup level (0.00295 mg/kg) with DRO non-detect. DRO concentration in soil reached 49.2 in HB05 but benzene was not detected. Monitoring well MP1 was installed in HB05 and all analytes in the ground water sample were either below instrument detection or below Table C cleanup levels. Since the pocket of contaminated material (historical) that did exceed human health risk levels for direct contact and ingestion is underground, beneath an asphalt cap, and has not migrated to groundwater then the migration to groundwater pathway is incomplete. The 2007 data indicate that any remaining soil contamination is de minimis in both concentration and volume.

Bruce Wanstall

2/2/2012

Exposure Tracking Model Ranking

A new updated ranking with ETM has been completed for source area 77852 USTs.

Bruce Wanstall

2/29/2012

Cleanup Complete Determination Issued

Based on the information provided to date, the DEC has determined that the contaminant concentrations remaining on site do not pose an unacceptable risk to human health or the environment. No further remedial action is required at this site. This determination is in accordance with 18 AAC 78.276(f) and does not preclude DEC from requiring additional assessment and/or cleanup action if future information indicates that this site may pose an unacceptable risk to human health or the environment.

Bruce Wanstall

3/12/2012

Update or Other Action

Project manager changed from Bruce Wanstall to IC Unit.

Evonne Reese

6/21/2013

Institutional Control Compliance Review

IC compliance review conducted. Reminder system set-up to follow-up with the responsible party in 2016.

Kristin Thompson

3/18/2016

Institutional Control Compliance Review

IC compliance review conducted. IC reminder letter drafted and scheduled to send out next year as part of this site's five-year review.

Kristin Thompson

5/18/2017

Institutional Control Compliance Review

IC compliance review conducted. ICs Verification letter issued. Reminder system set for future follow-ups to occur every three years.

Kristin Thompson

Contaminant Information

Name

Level Description

Media

Comments

GRO

< Method 2 Most Stringent

Soil

DRO

< Method 2 Most Stringent

Soil

Benzene

Between Method 2 Migration to Groundwater and Human Health/Ingestion/Inhalation

Soil

Control Type

Type

Details

Land Use Plan / Maps / Base Master Plan

A deed restriction agreement for future development on properties at the Sitka Airport managed by the ADOT&PF Airport Property Lease Division establishes restriction against accessing groundwater by requiring coordination with the DEC prior to installing any wells. Water and sewer are supplied to the area by the City of Sitka Public Works Department.

Requirements

Description

Details

Groundwater Use Restrictions

Development of drinking water wells is prohibited.

Other

The monitoring wells currently installed at the property that are not needed for area-wide monitoring must be decommissioned in accordance with ADEC guidance as soon as it is determined these wells are no longer needed.

Advance approval required to transport soil or groundwater off-site.

Standard condition.

Movement or use of contaminated material (including on site) in a manner that results in a violation of the water quality standards is prohibited (18 AAC 70)

Missing Location Data

Because the GIS location data for this site has not been entered, we cannot direct you to its position on the map. Click "Continue" to proceed to the Contaminated Sites Web Map or "Close" to return to the site report.